1. Field of the Invention
The present invention relates to non-volatile switching elements, a method of manufacturing the non-volatile switching elements, and an integrated circuit that includes the non-volatile switching elements.
2. Related Art
In an integrated circuit including cells for performing switching electrically, a transistor formed with a semiconductor material is most often used to serve as a switching element. As the gate insulating film of each transistor has become thinner with the miniaturization of semiconductor circuits in recent years, it has become difficult to restrain excess power consumption, even in a CMOS, due to the increases in leakage current.
Meanwhile, DRAMs (Dynamic Random Access Memories) and SRAMs (Static Random Access Memories) are most often used as volatile memories. Flash memories are most often used as non-volatile memories. However, MRAMs (Magnetic Random Access Memories), FRAMs (Ferroelectric Random Access Memories), OUMs (Ovonic Unified Memories), and RRAMs (Resistive Random Access Memories) have been proposed as memories with possibly improved characteristics (see the specification of U.S.P Application Publication No. 2004/0188668, for example).
However, DRAMs have problems such as scaling, SRAMs have problems such as large cell areas and power consumption, flash memories have problems such as long writing time, MRAMs have problems such as large power consumption, and FRAMs have problems such as scaling and poor reliability. As for OUMs and RRAMs, they are still being developed.
On the other hand, thermistors formed with materials that exhibit variations in electric resistance with temperature changes have been known over a long period of time, and have been used in current limiters, current-decay noncontact switches, temperature detectors, fixed-temperature heat generators, temperature sensors (infrared detectors), and the likes. However, there is no need to integrate those devices, or there is a heat source outside each of those circuits.
Although known to have variations in resistance with heat, thermal electric switching elements with heating sources or cooling sources have not been considered to be integrated to form a non-volatile memory or a logic circuit.
Also, a metal-insulator transition with a hysteresis is known in V2O3 oxides (see Physical Review B, Volume 22, Number 6, 1980, p.p. 2626, for example). In this paper, however, applications to non-volatile memories or logic circuits are not discussed, though the principles of a metal-insulator transition in V2O3 oxides are described